using java to find the location of the "\" char in a string

caged · 02-02-2004, 10:28 AM

i want to make a helper method in java that searches through a string and outputs the last place in the string where it finds the "\" charector. its tricky cos "\" is used in a java string to signal that an operation is being ordered eg"\n" is a break line command.

searching for "\" has no sucess neither does looking for "\\".

i have though about breaking the string into an array of type char but this is gonna slow down my program and its a bit ugly. any ideas how i can get around this easier.

cheers.
Ben.

Looking_Lost · 02-02-2004, 11:49 AM

If you want to use a backslash in a string it has to be escaped anyway like \\ so

char backslash='\\';

String testString=new String("123\\56\n78\\9");

System.out.println("\\ Appears last in position " + testString.lastIndexOf(backslash));

will return an index of 9 (return index starting at zero)

Is this what you mean?

caged · 02-02-2004, 07:11 PM

on the same track but well what i want this part of the program to do is...

take a location like "C:\documents and settings\ben\desktop\name" and subString the string so that only "\name" is left. the location is provided in this case from a DOS cmd piping dir into a text file and then java opens the text file and formats it and outputs an index.html file.

Code:

set classpath = 
dir > temp.txt
copy c:\code\FormatText.class FormatText.class
java FormatText.class
del temp.txt
del FormatText.class

^thats not all the code but you get the idea

since i cant change the string provided from the DIR command i could pipe the current directories name into the file before the DIR command. are there any prebuilt methods in java so i can easily insert the current directories name as a string.

Linux is obviously better suited to cope with this problem but i want my program to work on both platforms.

cheers.
Ben.

Mohsen · 02-02-2004, 10:56 PM

how about this:

String str = "c:\\salaam\\folder";
System.out.print(str.lastIndexOf('\\'));
str = str.substring(sd.lastIndexOf('\\'));
System.out.print(str);

Looking_Lost · 02-03-2004, 01:04 AM

Or take a look at the File class which has methods for returning the file name part, path name part etc. as a string

caged · 02-03-2004, 05:47 AM

Quote:

Originally posted by Mohsen
how about this:

String str = "c:\\salaam\\folder";
System.out.print(str.lastIndexOf('\\'));
str = str.substring(sd.lastIndexOf('\\'));
System.out.print(str);

yeah that would work but first i would have to change "C:\salaam\folder" into "c:\\salaam\\folder" as far as i know that would also require finding the "\" charactor and turning that into a "\\" charactor or charactors. do you know or have an idea how i could just pass "\\"?

Quote:

originally posted by Looking_Lost
Or take a look at the File class which has methods for returning the file name part, path name part etc. as a string

thats not a part of java i know anyhting about im researching at the moment thanks dude.

cheers.
Ben

llama_meme · 02-03-2004, 05:59 AM

You only need to escape backslashes in a string literal, not if you've got the string from some other source.

Alex

caged · 02-03-2004, 06:17 AM

ok in this case i got the string from: (pseudo)

Code:

readln of file input.txt into string blahBlah
if blahBlah.indexOf("Directory")  is not equal to NULL
then (
   a String called "title" is equal to substring(blahBlah + 13);
)
end if

so the "\" charactors in the string title are not implying to the interpretor that a formatting control/escape char is next????

cheers.
Ben.

llama_meme · 02-03-2004, 10:42 AM

Well in that pseudocode title is a literal string (although it's hard to tell form pseudocode), so yes any \s in it will be seen as escape characters. But if you read in a string from a file, say, which contains \s, those \s won't be treated as escapes. I thought you might be getting confused over that, I'm sorry to mention it if you weren't.

Alex